The development of organic thin film transistors (OTFTs) has grown rapidly in recent years motivated primarily by the unique physical properties of polymer devices, including their flexibility and ability to be fabricated using low-cost, solution-based techniques. Work on developing OTFTs for new and existing applications has focussed on two main areas. First, there have been systematic improvements in the materials and fabrication processes which have lead to an improvement in the conventional performance parameters of organic devices making them comparable to their inorganic counterparts. Second, improvements in film morphology of the organic semiconductor layer have been made with the goal of eliminating electron and/or hole traps and enhancing free carrier transport in the polymer semiconducting materials. Progress has also been made in developing high capacitance organic dielectric layers and large improvements in OTFT performance have been reported. The inherent compatibility of organic materials with biological molecules makes OTFTs suitable for use in biosensing applications.
The present inventors have successfully fabricated an OTFT device that is capable of sensing glucose levels across a broad range of concentrations and which is straightforward and cheap to manufacture. The device opens the way for a commercially viable glucose sensor that allows blood glucose concentration to be estimated by detecting the level of glucose in saliva as opposed to blood. Such a device would obviate the need for diabetic patients to obtain a blood sample when determining their blood glucose level.